Comparison of the effects of histamine and N(alpha)-methylhistamine on neuronal function in the guinea-pig oesophagus and ileum.
The effects of histamine and N(alpha)-methylhistamine, two components of gastric juice, on vagal and transmural stimulation of the guinea-pig isolated oesophagus were compared with their effects on cholinergic and on non-adrenergic-non-cholinergic (NANC) neuronal responses in the isolated ileum, both tissues having been pretreated with mepyramine (1 microM). Histamine (< or = 10 microM) and N(alpha)-methylhistamine (< or = 1 microM) had no significant effect on either vagal or transmural stimulation in the oesophagus. Substance P, which produces a contraction by activation of cholinergic nerves in the oesophagus also was unaffected by histamine. In contrast, the agonists inhibited contractions produced by cholinergic nerve stimulation in the ileum; the inhibition produced by histamine (10 microM) was up to 73 +/- 5%, that by N(alpha)-methylhistamine (1 microM), 48 +/- 5%. Histamine also inhibited responses to stimulation of NANC neurons by up to 37 +/- 14%. The effects of histamine and N(alpha)-methylhistamine in the ileum were inhibited by clobenpropit (0.1 microM). These findings suggest that histamine and N(alpha)-methylhistamine have no role in the modulation of neuronal function in the oesophagus, in contrast with their effect in the ileum.
Hemedah
M
M
Department of Pharmaceutical Biology and Pharmacology, Victorian College of Pharmacy, Monash University (Parkville Campus), Australia.
Mitchelson
F
F
D000109:Acetylcholine / Q000494:pharmacology; D000818:Animals; D001285:Atropine / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004558:Electric Stimulation; D004947:Esophagus / Q000294:innervation*; D006168:Guinea Pigs; D006632:Histamine / Q000378:metabolism* / Q000494:pharmacology; D006633:Histamine Antagonists / Q000494:pharmacology; D007082:Ileum / Q000294:innervation*; D007093:Imidazoles / Q000494:pharmacology; D066298:In Vitro Techniques; D008761:Methylhistamines / Q000378:metabolism* / Q000494:pharmacology; D018482:Muscle, Skeletal / Q000187:drug effects / Q000294:innervation; D009130:Muscle, Smooth / Q000187:drug effects / Q000294:innervation; D009474:Neurons / Q000187:drug effects / Q000378:metabolism*; D009475:Neurons, Afferent / Q000187:drug effects / Q000502:physiology; D011738:Pyrilamine / Q000494:pharmacology; D011950:Receptors, Cholinergic / Q000187:drug effects / Q000502:physiology; D018040:Receptors, Neurokinin-1 / Q000187:drug effects / Q000502:physiology; D018042:Receptors, Neurokinin-3 / Q000187:drug effects / Q000502:physiology; D013373:Substance P / Q000494:pharmacology; D013779:Tetrodotoxin / Q000494:pharmacology; D013890:Thiourea / Q000031:analogs & derivatives / Q000494:pharmacology; D014630:Vagus Nerve / Q000187:drug effects / Q000502:physiology*
D006633:Histamine Antagonists; D007093:Imidazoles; D008761:Methylhistamines; D011950:Receptors, Cholinergic; D018040:Receptors, Neurokinin-1; D018042:Receptors, Neurokinin-3; D013373:Substance P; D013779:Tetrodotoxin; D001285:Atropine; D006632:Histamine; D013890:Thiourea; D011738:Pyrilamine; D000109:Acetylcholine; C086108:clobenpropit; C048140:N-methylhistamine